Objective: This study examines whether severity and the functional impact of cognitive decline in Parkinson’s disease mild cognitive impairment (PD MCI) participants differ between those with and without REM sleep behavior disorder (+RBD, -RBD; respectively).

Background: RBD is common in PD and has been associated with worse cognitive function. Although RBD is associated with a higher risk for MCI in PD, the specific association between RBD and cognition in those that have MCI has not been investigated in a matched group of PD participants.

Method: The data was obtained from the National Alzheimer’s Coordinator Center for the Uniform Data Set (1) for data collected from September 2005 to December 2020, from 20 Alzheimer’s Disease Research Centers. We included participants clinically diagnosed with PD MCI at baseline and assessed for RBD by the clinician. Participants with a clinical diagnosis other than PD as the primary cause of cognitive decline at any visit were excluded. These criteria provided a sample of 60 participants. The participants with and without RBD were matched by age, education, sex, and race leading to a sample of 58 participants (+RBD=27, -RBD=31). CDR^® Dementia Staging Instrument (CDR) scores were compared between +RBD and -RBD groups. p-values were corrected for multiple comparisons.

Results: Age at PD diagnosis was similar for +RBD and -RBD groups (p=0.770). +RBD participants scored significantly worse on CDR Sum of Boxes (p=0.003, Figure 1) compared to     -RBD PD MCI participants. Specifically, CDR Home and Hobbies and Community Affairs scores were significantly worse in +RBD participants (p=0.002, p=0.014; respectively, Figure 1). Scores on other CDR domains and the CDR Global scores did not differ for +RBD and -RBD participants.

Conclusion: In PD MCI participants with similar demographics and age at PD diagnosis, those with and without RBD had similar decline in memory, orientation and executive functions. However, life at home and in the community was more impaired for participants with RBD, suggesting an association between RBD and the functional impact of cognitive decline. Further studies should examine the impact of RBD on quality of life in PD patients at all stages of disease progression to adequately address daily life functioning.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-functional-impact-of-rem-sleep-behavior-disorder-in-parkinsons-disease-with-mild-cognitive-impairment/